Sound-wave transmitting and amplifying device



Dec. 31, 1 929. w. HARDEN 1,741,934

SOUND WAVE TRANSMITTING AND AMPLIFYING DEVICE Filed Aug. 29, 1927 INVENTOR. WEI/T54 BQK A TTORNE Y.

Patented Dec. 31,1929 I UNITED STATES PATENT OFFICE WALTER HABDEN, 01' CINCINNATI, OHIO, ABSIGNOR O1 ONE-THIRD "1'0 JOHN I. HOL- LAND AND ONE-THIRD TO WILLIAM I. HOLLAND, BOTH OI CINCINNATI, OHIO SOUND-WAVE TBANBII'ITING AND AMPLIIYING DEVICE Application filed Auznat 89, 1927. Serial No. 816,176.

The invention relates to means adapted to reproduce and amplify. the volume of the sound waves produced by stringed musical instruments. I

Heretofore, considerable difiiculty has been experienced by the makers and-users of (18-, vices utilized to amplify the sound vibrations of stringed-musics. instruments in satisfactorily amplifying the musical tones, because of the fact that the sounds produced by the strings which have almost ceased vibratin intermingle with and disadvantageously a feet the musical tones produced by the strings intended by the player to produce 1 music, whereby the quality of the amplified music is importantly reduced. Also, the normal audible and inaudible vibrations of the strings usually are transmitted'to the sound box to be amplified, as well as other vibram tions of the box, as produced by the touch of the player, as a result of the amplified sound waves noticeably contain various undesirable noises.

The objects of the invention are to provide 25 a simple, efiicient and economical strin ed musical instrument havin connection with a transmitter and amp ed, whereby the vibrations of the respective, strings are individually transmitted to the transmitter; and

30 to provide means to prevent amplification of the vibrations of-the sound box.

Other objects of the invention will become vapparent by reference to the hereinafter description.

The invention consists in the combination of the elements, the arrangement of the parts, and in the details of the construction, as hereinafter specified and claimed.

In the drawings Fig. 1 is a plan view of the invention with parts broken away;

Fig. 2 is a section taken on the line 2-2 in Fig. 1, with parts broken away; and

3 is a section taken on the line 3-3 in Fi 1, with parts broken away.

fn the preferred construction of the invention I provide the guitar type musical instrument 1 consisting of the box 1 comprising the top 2 and the bottom 3 secured n parallel spaced apart relation as by the side strip 4 having its u per and lower edges 5 and 6, re-

spectively, and bottom.

Secured to the front 7 of the box is the neck 8 having the front ends 9 of the strin 10 secured thereto in a manner usual with this type of instrument. The neck is insulated from sound vibrations from the box 1' as by rubber strip 8, to prevent transmission of the vibrations of the front ends 01 the strings to the box.

The rear ends 11 of the strings 10 are suitably secured to the tail pieces 12 having their outer ends 13 suitably secured or connected to the rubber blocks 14 suitably fixed to the upper edge of the rear of the strip 4, whereby vibrations of the strings 10 are prevented from beingtransmitted by the rear ends of the stringsto the box 1'. a

Secured to the bottom 3, of the box 1, as by screws 15, are the spaced apart U-shape supports 16 and 17 having their tops 18 ositioned directly beneath the rectangiilar old 18' in the to and extending para el to the strings 10. he round sound hole 19 in the to is adjacent the hole 18'.

guitably fixed to the outer ends of the tops 18 of the supports 16 and 17 and extending from one support to the other are the bars 20 and 21 having fixed to their upper sides the vibration non-conducting strips 22 and 23, formed of sponge rubber or the like material. Suitably secured to the upper sides of the strips 22 and 23 are the spaced apart plates 24 positioned directlybeneath the respective strin 10. Suitably secured to the upper sides 0 the plates 24 are the blocks 25 a 'gned diametrically of the hole 18 in the top. Suitably secured to the up r sides of the blocks 25 are the ends 26 of t e vibration conduction rods 27 whose bodies 28 extend at right angles to the ends 26 and inwardly of the box. Fixed to the lower ends 29 of the rods 27 is the vibration conduction stafi 30 having fixed thereto the clamp 31 comprising the retainer 32 having therein at 33 a hole adapted to receive the upper end 34 of the ed to the outer e ges of the top transmission rod 35 having its lower end 36 threaded to the nut 37 suitably fixed to the diaphragm 38 of the usual microphone or transmitter 39 fixed to the upper side 40 of the sound vibration non-conductor 41 formed of spon e rubber or the like material. The non-con uctor 41 is secured to the upper surface 41 of the bottom 3 of the box 1 The transmitter 39 may be of any suitable construction to facilitate in clearly and efiectually reproducing the tones of the strings 10 of the instrument 1 by methods hereinafter ex lained.

he transmitter 39 mayconsist of the casing 42 having suitably arranged therein a magnet (not shown), having wound thereabout a coil (not shown), the ends of which are connected with conductors 43 and 44 which enter the casing through the hole 45 in the side thereof.

For the purpose of reproducing andamplifyin the tones of the strings 10, of the musica instrument 1, any suitable device, circuit or arrangement of elements may be utilized.

One form of a usual reproducing and amplifying device is represented by the diagrammatical view shown in Fig. 3, in which conductors 43 and 44, of the transmitter 39, are respectively connected with the amplifier 46 having connection, through conductors 47 and 48, with the usual reproducing or loud speaker element 49.

It is apparent that various sta es of transformer cou led, resistance coup ed or other forms of sultable amplification, as desirable, may be incorporated in the circuit shown to increase the volume of the tones from the strings 10.

It 1s preferable that the transmission rod 35 is of serpentine form, as shown in Fig. 2, whereby when the upper end 34, of the transmission rod is properly adjusted in the hole at 33, in the retainer 32, the thumb-screw 50, threaded in the retainer, may be manually screwed inwardly in secure engagement with the transmission rod to retain the latter in fixed position with relation to the stafi 30. Also, the serpentine rod acts as a damper.

The strings 10 are in contact with the ends 26 of the rods 27, in the same manner as the strings of musical instruments of the guitar ty e are in engagement with the usual bridge.

uring playing of the musical instrument 1 the vibrations of the strings 10 are transmitted through the rods 27, staff 30, retainer 32, transmission rod 35, and nut 37 to the diaphragm 38 of the transmitter 39, whereby through the amplifying means previously described the sound vibrations produced b the strin s 10 are amplified Without ampli ying the vlbration from the box 1'.

It is a parentthat I have invented a practical an highly desirable invention for the purposes intended, and which may be utilized to efiect amplification of theihusical tones particularly of the strings of musical instruments. Moreover, if desirable, only selected number of instruments are used without amplification of the normal sound vibrations.

It will now be apparent that I have devised a novel and useful structure, which embodies the features of advantage enumerated as desirable in the statement of the invention and the above description, and while I have, in the resent instance, shown and described a pref rred embodiment thereof which will give in practice satisfacto and reliable results, it is to be understoo that the same is susceptible of modification in various particulars without departing from the spirit of the invention or sacrificing any of its advanta es.

%Vhat I claim asnew and desire to secure by Letters Patent is: r

1. In a device of the class described, a box comprisin a spacedapart bottom and a top having a ole therein, means securing said top and bottom in spaced apart relation,a neck secured to said box and sound insulated therefrom, spaced apart strin s capable of vibrating secured to said necE and said box and sound insulated therefrom, a pair of spaced apart supports secured to said bottom and positioned beneath said hole, a pair of spaced apart bars having their ends secured to the tops ofsaid supports,vibration non-conductor strips secured to said bars, a plurality of plates having their ends secured to said strips and positioned beneath said strings, respectively, a plurality of spaced a art vibration conductor rods secured to said lates and having said strings respectively 1n engagement therewith, a vibration conductor secured to said rods, a transmitter secured to said bottom and insulated therefrom, and a transmission rod operatively connectin said staff with said transmitter, substantia ly as described. I

2. In combination with a stringed musical instrument of the guitar type, a transmitter sound insulated from the box ofsaid instrument, an electrical amplifying circuit for said transmitter, a plurality of spaced apart vibration conductors operatively connected with said transmitter and with the strings of said instrument, substantially as described.

3. A vibration rod of serpentine form for an instrument of the guitar type, a microphone operativelyconnected with said rod, means whereby the strin s ofsaid instrument are in en a ment wit said rod, means e whereby t e x of said instrument is sound having a insulated from said rod, and means to repro- 'having a hole therein, means securin said duce the sound vibrations of said strings.

4. In a device of the class described a box comprising a spaced apart bottom and a top having a hole therein, means securing said top and bottom in spaced apart relation, spaced apart strings capable of vibratin secured to said box, a pair of u-shape space apart suports secured to said bottom and positioned neath said hole, a pair of spaced apart bars having their ends secured to the tops of said supports means secured to said bars, a plura ity o spaced apart vibration conductor rods supported by said last mentioned means and havin said strings respectivel in engagement therewith, a vibration sta secured to said rods, a transmitter, a transmission rod operatively connecting said staff with said transmitter, and electrical amplifying means connected with said transmitter.

5. In a device of the class described, a box comprising a spaced apart bottom and a top having a hole therein, means securing said to and bottom in spaced apart relation, space apart strings capable of vibrating secured to said box and sound insulated therefrom, a pair of spaced apart sup orts secured to said ottom and positioned eneath said hole, a pair of spaced apart bars having their ends secured to the tops of said su ports, vibration non conductor stri s secure to said bars, a plurality of plates avin their ends secured to said strips and positloned beneath said strings, res ectivel a plurality of spaced a art vibration con uctor rods secured to said p ates and having said strings respectively 1n enga ement therewith, a stafi secured to said r s, a transmitter secured to said bot- .tom and vibration insulated therefrom, and a transmission rod of serpentine form operatively connecting said staff with said transmitter, substantially as described.

6. In a device of the class described, a box comprisin a spaced apart bottom and a to ole therein, means securin sai top and bottom in spaced apart reEation, spaced apart strings capable of vibrating'secured to said box and sound-vibration insulated therefrom, a pair of spaced apart suports secured to said bottom and positioned neath said hole, a pair of spaced apart bars having their ends secured to the tops of said supports, vibration non-conductor strips secured to said bars, a lurality of plates having their ends secure to said strips and ositioned beneath said strin respectivel a plurality of spaced apart vibration conductor rods secured to said plates and having said strings respectively in en agement therewith, a stafi' secured to said rods, a transmitter and a transmission rod operatively connecting said stafi with said transmitter substantially as described.

7. In a device of the class described, a box comprising a spaced apart bottom and a top top and bottom in spaced a art re ation, spaced apart strings capable o vibrating secured. to said box and sound-vibration insulated therefrom, a pair of spaced apart suprts secured to sald'bottom and positioned hzneath said hole, a pair of spaced apart bars having their ends secured to the tops of said supports, vibration non-conductor strips secured to said bars, a lurality of plates having their ends secure to said strips and sitioned beneath said strin s, respective y, a plurality of spaced apart vibration conductor rods secured to said plates and having said strin s respectively in en agement therewith, a sta secured to said rods, a retainer fixed to said staff and having a hole therein, a transmitter, a transmission rod of serpentine form having its upper end received in said last mentioned ho e, the lower end of said transmission rod operatively connected with said transmitter, and means to retain said transmission rod in adjusted position in said hole in said retainer.

' WALTER HARDEN. 

